1. Field of the Invention
This invention is concerned with upgrading heavy crude oil. It is particularly concerned with deasphalting whole crude, before any high temperature thermal processing, to produce a deasphalted crude with a reduced metals content.
2. Description of the Prior Art
The world's supply of light, sweet crudes has greatly diminished in recent years. Refiners have been forced to deal with ever heavier crudes, containing significantly more metals, while still producing a full spectrum of products. Much of the problem of upgrading these heavier stocks is due to the presence of so much metal, usually nickel and vanadium. The presence of large amounts of metal, usually in association with asphaltenes, presents a formidable upgrading challenge. Some of the worst of these materials are "heavy crudes" while almost as bad are somewhat lighter crudes which contain less asphalt, but even more metal. Each type of resource will be briefly reviewed.